The present invention relates to an articulated device for the guidance and levitation of a rail vehicle, the said device being composed of a deformable support equipped with at least four independent wheels and comprising a horizontal substantially crossmember secured to this vehicle body, so as to be perpendicular to the longitudinal axis of the body in the vicinity of one end of this body, and two longitudinal members, each equipped with at least two wheels and mounted longitudinally on a substantially vertical pivot of an articulated element carrying the crossmember on either side of a vertical plane containing this longitudinal axis, so as to be directionally pivotable in a horizontal plane and, on the other hand, tiltable in a vertical plane in order to make it possible for the wheels carried by the longitudinal members connected to one another by means of a ball-mounted link to follow the curves of the track and pass over the inequalities of the latter.
It is used mainly in urban transport, especially when the route has curves of small radius, when the track infrastructure requires light-weight and compact guidance and levitation devices, or when traffic corridors which are low and of large width have to be arranged in line with the said devices.
A large number of devices for the levitation of rail vehicles, capable of ensuring the dynamic stability of these vehicles, both along a straight path and along a curved path, is already known.
European patent No. 60,000 describes a device for the levitation and guidance of a rail vehicle, equipped with at least four wheels mounted on a support intended to be secured to the body of a vehicle in the vicinity of one end of this body.
This device is composed of a crossmember maintained perpendicular to the vertical plane containing the longitudinal axis of the vehicle and of two longitudinal members which, in the operating position, are arranged in the longitudinal direction of the body on either side of the abovementioned vertical plane. These longitudinal members are connected to one another by means of a ball-mounted linkage. They are articulated on the common crossmember by means of vertical pivots capable of assuming a certain inclination in the substantially vertical longitudinal plane. These pivots are connected to one another by means of ball joints and a rocker fixed to the crossmember by means of a pivot perpendicular to the plane formed by the crossmember and the longitudinal axis of the vehicle.
On bends or curves, the long.itudinal members pivot relative to the crossmember about substantially vertical pivots and form the opposite sides of a deformable trapezium, whilst the crossmember remains perpendicular to the longitudinal axis of the vehicle body.
Belgian patent 8,700,527 describes a device similar to that described in the abovementioned European patent. Each of the two longitudinal members carrying the independent wheels is composed of two sections articulated about vertical pivots, each section carrying at least one wheel and being directionally controlled by a system of ball-mounted linkages.
On bends or curves, the sections of the longitudinal members pivot relative to the crossmember and relative to their other section and form the sides of two deformable trapezia, whilst the crossmember remains perpendicular to the vehicle body, the advantage of this second device over the first being that each wheel is oriented tangentially relative to the track portion on which it bears.
In both devices, because the longitudinal members oscillate directionally about two separate pivots, the distances between the planes of the left and right wheels decrease progressively at the start of travel in a straight line and on sharp bends reach values incompatible with those of the track, so that travel on a track of small radius of curvature, with grooved rails and non-worn wheels, becomes impossible without causing jamming and risking derailment.